Face recognition may involve qualitatively different mechanisms from other object recognition. One of the markers for that assertion is the face inversion effect, showing that face recognition is more sensitive to orientation than that for other objects. Inversion may particularly disrupt the processing of configural information, such as the second-order spatial relations of facial features. The aim of our study was to further investigate the contribution of features and configuration in facial representations by studying face identity aftereffects.

We used three types of stimuli: whole faces, ‘exploded’ faces (disrupted second-order relations but preserved first-order relations) and ‘scrambled’ faces (disrupting first-order relations). Whole and altered faces served as adapting or test stimuli, viewed either both upright or both inverted. We measured perceptual-bias aftereffects in identity judgments regarding ambiguous morphed test face stimuli. Our primary goal was to determine the degree of adaptation that altered faces could induce in whole faces and whether this varied with orientation. Fourteen healthy subjects participated.

Compared to whole-face adaptors, exploded faces induced partial aftereffects in whole test faces and these showed an inversion effect similar to those seen with whole-face adaptors. In contrast, scrambled faces were ineffective at adapting whole-face test stimuli in either orientation, although they could induce aftereffects in scrambled-face test stimuli.

We conclude that disruption of second-order spatial relations does not prevent facial features from engaging facial representations of identity, but that a proper first-order relationship of features is an essential prerequisite. Second-order spatial relations do form an integral part of face representations as disrupting these reduces the magnitude of the face aftereffect.